> On Feb 13, 2018, at 4:02 PM, array chip via R-help <r-help@r-project.org> > wrote: > > Hi all, > > The survdiff() from survival package has an argument "rho" that implements > Fleming-Harrington weighted long rank test. > > But according to several sources including "survminer" package > (https://cran.r-project.org/web/packages/survminer/vignettes/Specifiying_weights_in_log-rank_comparisons.html), > Fleming-Harrington weighted log-rank test should have 2 parameters "p" and > "q" to control the weighting for earlier vs later times in the follow-up. > > For example, setting rho=1 in survdiff() uses the Peto-Peto modification of > Gehan-Wilcox weights, which I can confirm by setting p=1 & 1=0 in comp() from > survminer package. similarly rho=0 is equivalent to p=0 & q=0 > > I am interested in putting more weights on survival difference in later > follow-up time. According to comp() from survminer package, that would set > p=0 & q=1 for Fleming-Harrington weights. > > My question is how I can do the same by setting certain values for "rho" in > the regular survival() function?
I think that survdiff uses a different version than what you have found. The G-rho family weights are: w_j = [Sˆ(tj)]^ρ So rather than two parameters on S(t) and (1-S(t)) as in the p,q version, you only have one parameter applied to S(t). This class handout says that the G-rho,gamma weighting scheme is not available in survdiff. -- David Winsemius Alameda, CA, USA 'Any technology distinguishable from magic is insufficiently advanced.' -Gehm's Corollary to Clarke's Third Law ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
